| 摘要 |
PROBLEM TO BE SOLVED: To provide a hands-free intercom device capable of smoothly perform a two-way call even when noise around an entrance or indoors is loud concerning the hands-free intercom device. SOLUTION: The hands-free intercom device includes an entrance slave unit and a hands-free intercom master unit. The hands-free intercom mater unit is constituted of a call path switcher which forms a two-way call path between the hands-free intercom master unit and the entrance slave unit. The call path switcher includes: a transmitted voice intensity calculation unit that performs fast Fourier transform of an indoor transmission signal to calculate a signal which can be observed to third harmonic as transmitted voice intensity; a received voice intensity detection unit that performs the fast Fourier transform of a received signal around the entrance to calculate the signal which can be observed to the third harmonic as received voice intensity; a comparison unit that compares the transmitted voice intensity and the received voice intensity; and a switcher that switches the transmitted signal to the entrance slave unit and the received signal from the entrance slave unit. COPYRIGHT: (C)2011,JPO&INPIT |
